<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>系统升级中</title>
    <meta name=viewport content="width=device-width,user-scalable=no,initial-scale=1,maximum-scale=1,minimum-scale=1">

    <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
    <meta http-equiv="Pragma" content="no-cache" />
    <meta http-equiv="Expires" content="0" />
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        html,body,div {
            width: 100%;
            height: 100%;
        }
        img{
            display: block;
            position: absolute;
            left: 50%;
            top: 50%;
            transform: translate(-50%,-50%);
        }
        div{
            background-color: #eee;
        }
    </style>
</head>

<body>
    <div> 
        <img src="" alt="">
    </div>
</body>

</html>